The invention is directed to a method and to a circuit arrangement for transmitting message cells occurring with a first transmission bit rate on an offering trunk during at least one virtual connection or at least one virtual path.
Such a method and such a circuit arrangement have been set forth in European Patent Application 92 11 4798.9, corresponding to Hill Firm U.S. Case No. P-93,1565, U.S. Ser. No. 08/111,000, filed Aug. 24, 1993. It is provided therein that the message cells belonging to a virtual connection are first depacketed. The message signals contained in the message cells are subsequently divided into successive signal sections whose respective bit plurality if uniformly defined such that this bit plurality, plus a defined plurality of information bits, corresponds to the plurality of bits transmittable as useful signals in the information part of a message cell. These signal sections are then successively inserted into the information parts of message cells, whereby a continuously changing signal section sequence number is respectively entered into the information parts as information bits. These message cells are then successively distributed onto a plurality of inputs of an ATM network that corresponds to the bit rate ratio of the first transmission bit rate to the second transmission bit rate, and are transmitted via the corresponding inputs to outputs of the ATM network allocated thereto. The signal section respectively contained in the message cells appearing at the corresponding outputs as well as the signal section sequence number belonging thereto are taken from the message cells appearing at the corresponding outputs. Message signals whose bit plurality respectively corresponds to the plurality of bits transmittable as useful signals in the information part of a message cell are then formed from the sequence of the signal sections for the respective virtual connection. Subsequently, the message signals are successively inserted into message cells referring to the respective virtual connection. These message cells are forwarded on with the original transmission bit rate.
Beyond this, a method has already been disclosed for switching message cells of a transmission system transporting a message cell stream according to an asynchronous transfer method via a switching network constructed with modules (European Patent Application 91 10 7434.2, corresponding to U.S. Pat. No. 5,317,561. The transport bit rate of the transmission system amounts to a multiple of the switching elements of the modules. Upon respective attachment of information, message cells to be switched are thereby distributed onto a plurality of switching network inputs that corresponds to this multiple. This information indicates all those modules via which the respective message cells should be through-connected to an output of the switching network. The message cells transmitted to various outputs are then recombined to form a message cell stream. Among other things, it is provided that a cyclically successive sequence number is attached to the message cells before the through-connection through the switching network, the sequence of the message cells for every connection being assured on the basis of this sequence number when they are combined to form the message cell stream. The message cells are cyclically distributed onto the switching network inputs.